dB Attenuator Calculator

To use this tool, enter the desired value of dB attenuation and the characteristic impedance (default value is 50 ohm). The tool computes resistor values in different configurations:

• Pi Attenuator
• T Attenuator

Pi Attenuator Calculator

Formula

R₁ = Z_o [10^dB/20 + 1] / [10^dB/20 – 1]

R₂ = Z_o/2 [10^dB/10 – 1] / [10^dB/20]

where R1 is the shunt resistor (to ground) and R2 is the series resistor. To build this attenuator you will need

• two shunt resistors – one at the input and the other at the output
• one series resistor

T Attenuator Calculator

Formula

R₁ = Z_o [10^dB/20 – 1] / [10^dB/20 + 1]

R₂ = (2*Z_o)*[10^dB/20] / [10^dB/10 – 1]

where R1 is the series resistor and R2 is the shunt resistor (to ground). To build this attenuator you will need

• two series resistors – one at the input and the other at the output
• one shunt resistor